In a small heavy-based saucepan, heat the chicken stock over high heat until hot, but not boiling. Cover and keep warm.

Meanwhile, heat a large, heavy-based, non-stick, high-sided frying pan over medium heat. Add the oil and allow it to heat for 2 mins. Add the pumpkin and cook for 5 mins, or until it begins to brown. Add the fennel, onion and garlic and cook for 3 mins, or until the vegetables begin to soften. Add the rice and stir for about 1 min, or until it is well coated with oil and hot. Add the wine and stir constantly for about 1 min, or until most of the wine has evaporated. Stir in the lemon zest.

Add 1 cup of the hot stock to the rice mixture and cook, stirring almost constantly and keeping the mixture at a steady simmer, for about 2 mins, or until it is absorbed. Continue adding the hot stock, 1 cup at a time, stirring until each addition is almost completely absorbed before adding more, and cook for about 18 mins, or until the rice is al dente and creamy.

Stir in the prawns and cook, while stirring and adding more stock as needed, for about 4 mins, or until the prawns are just cooked through but still tender. Remove the pan from the heat and stir in the parsley and ½ c of the parmesan. Stir in lemon juice and season to taste with salt.

Divide the risotto among four wide serving bowls. Garnish with remaining parmesan and freshly ground black pepper, to serve.